Vault 108 is one of the 6 Vault-Tec vaults found in Fallout 3. It's located in the far east of the Capital Wasteland, to the south of Canterbury Commons. The vault is full of Mole Rats and human clones all called Gary (followed by a number). The Gary clones will be hostile towards you and none of them have any dialogue, the only thing they can say is "Gary". The vault was used to test human cloning, but each new clone that was created became more violent than the last. There were 54 clones in all and after they failed to fix the aggression problem the scientists gave up. It is unknown whether the scientists abandoned the vault or if they were over-thrown by the clones.